Numerous publications show a wide variety of designs for missiles. However, none of them is as simple, as cost-efficient and as effective in use as would be desired.
Exemplary designs include that shown in U.S. Pat. No. 511,418 to Gathmann, which shows a projectile in which a rear section 2 contains a charge of a propellant. When the propellant is ignited, the exhaust of the burning charge reacts against spirally arranged flanges 6 to impart spiral motion to the projectile in flight. The end of the chamber 2 containing the propellant is formed by a flat plug 8, which is forced from the end of the chamber upon ignition of the propellant.
U.S. Pat. No. 2,927,535 to Abramson et al shows a projectile which is apparently to be launched from a cannon or the like and which does not contain an internal propellant. The projectile is adapted to be rotated in flight by a "slipping driving means 17, 18".
U.S. Pat. No. 2,922,365 Fredette et al shows an aerial missile which is to be dropped from an airplane or the like, and which comprises external fins or spoilers 52 to stabilize its flight.
U.S. Pat. No. 3,390,850 to Dahlke et al shows a rocket having fins which pivot outwardly upon launching and which are stated to induce spin of the rocket in flight.
U.S. Pat. No. 2,405,415 to Eksergian shows a rocket projectile which also has outwardly pivoting fins 18 which cause it to spin in flight. The Eksergian projectile includes internal propellant 8 and shows a converging/diverging nozzle structure.
U.S. Pat. No. 2,500,537 to Goddard shows an aircraft comprising a combustion chamber which is mounted for rotation in flight, and which is connected to a converging/diverging nozzle member N.
Finally, U.S. Pat. No. 4,194,706 to Detalle shows a nozzle member which is apparently to be attached to a conventional converging/diverging nozzle for a missile and which comprises internal fin members 3 which are intended to cause the missile to rotate in flight.
From the above, it will have been appreciated that while the art teaches that it is desirable to spin projectiles in flight, such that their angular momentum can contribute to the accuracy of their trajectory, the devices proposed for doing so to date have been relatively complex and cumbersome. Furthermore, many designs have involved fins external to the fuselage of the missile, providing substantial aerodynamic drag penalties. These external fin devices also make it difficult to carry such projectiles in desired locations, e.g., under the wings of aircraft, both for reasons of space consumption and again because the external members add substantial aerodynamic drag, thus slowing the aircraft and making it less fuel efficient.
Furthermore, it will have been appreciated that each of the devices described above which employ combustion of an internal propellant for propelling the missile involve use of converging/diverging exhaust nozzles, as is nearly universal in projectile and rocket design.